List<VUsresrptitemcount> itemList = vUsresrptitemcountMapper.getRoomInfoCount1(null, start, end, hospitalCode, modality);
itemList 的元素是对象VUsresrptitemcount,现在根据对象里的房间进行分组
Map<String, List<VUsresrptitemcount>> map = itemList.stream().collect(Collectors.groupingBy(VUsresrptitemcount::getRiRoomname));
String 为房间名, List为每个房间对应的集合